Advanced Programming
Tsunami2 Electric User’s Guide
58
Control Loop Coefficients
Tsunami2 compensates for load changes in response to back-EMF voltage readings that
compare motor load to locomotive speed. When a variation between them occurs, a
proportional-integral (PI) control loop adjusts the motor voltage to compensate for the difference
so that the locomotive’s speed remains consistent. Adjust the PI control loop with CV 209 (PID
Kp Parameter) and CV 210 (PID Ki Parameter).
Kp Coefficient
CV 209 is used for adjusting the proportional gain of the control loop, and compensates for
dynamic changes in the motor load based on the contrast between the throttle setting and motor
speed. CV 209 may be programmed with a value from 0 to 255. Higher values indicate higher
levels of compensation. However, values that are too high may lead to inconsistencies in motor
control.
Ki Coefficient
CV 210 is used for adjusting the integral gain of the control loop, and compensates for static
changes in motor load by applying a correction based on the integral difference between the
throttle setting and the current motor speed. CV 210 may be set to a value from 0 to 255. Higher
values indicate higher levels of compensation and a more sensitive control loop. We suggest
setting CV 210 to the lowest value that still provides optimal performance; setting CV 210 to
values that are too high may lead to oscillations in locomotive speed.
Note:
Setting CVs 209 and 210 to values of 0 will disable the control loop.
Strategy for Optimizing Hyperdrive2
Finding the right combination of CV settings requires some experimenting and patience. Be
aware that these settings will inherently vary between locomotives. If you happen to make an
adjustment to an advanced motor control CV that compromises operation in some way, you can
reset CV settings with CV 8 (Manufacturer ID). Refer to “Introduction to Programming” for more
information.
Use your CV settings as starting points when configuring other locomotives. Adjusting a
particular setting can actually degrade performance, and therefore changes should be made in
small increments until you find your preferred result. And remember, the decoder’s default
settings should provide satisfactory performance for most situations.
Example: Adjusting the Control Loop
We suggest the following procedure to help fine-tune the CV settings:
1. Make sure all the Hyperdrive2 CVs are set to default values.
2. Set CV 2 (Vstart), CV 5 (Vhigh), and CV 6 (Vmid) to 0.
3. With the locomotive on level track, set the throttle to speed-step 20.
4. Increase the value of CV 209 until the locomotive’s speed becomes varied and choppy.
5. Reduce the value of CV 209 until speed is consistent, smooth, and without variance.
6. Increase the value of CV 210 until you notice the locomotive’s speed begin to oscillate.
7. Reduce the value of CV 210 until the oscillation stops.